Fan Control
Center
Replacement Description
The
ICM275
Gas Furnace Control Center is a new generation control for the
replacement market.
The
ICM275
Gas Furnace Control Center is designed to function similarly to previous
control center designs, while incorporating some of the latest features in furnace
control center technology.
It is a form, fit and functional replacement of the OEM control for the following Carrier
control center part numbers: HH84AA021, HH84AA001, HH84AA003, HH84AA005,
HH84AA009, HH84AA014, HH84AA015, or CESO110019.
•
Input Voltage
- Terminals: PR-1, PR-2, L1, L2 and COM ..................................................... 120 VAC
- Terminals: SEC-1 and SEC-2 ................................................................... 18-30 VAC
•
Line Frequency
..................................................................................................60 Hz
•
Operating Temperature
..................................................................... -40ºF to +176ºF
•
Maximum Operating Humidity
....................................................................95% R.H.
Non-condensing @ 50ºC
•
Time Delays
- Heat
ON
.................................................................................................. 60 Seconds
- Heat
OFF
......................................................................................... 60-240 Seconds
- Cool
OFF
(R18 Cut) ................................................................................ 90 Seconds
Specifications
This application guide covers the installation of the Gas Furnace Control Center, Part
No.
ICM275
, in an intermittent ignition, induced draft, or condensing gas furnace.
Introduction
Installing and servicing heating equipment can be hazardous due to gas and electrical
components. Only trained personnel should install or service heating equipment.
Untrained personnel can perform basic maintenance functions such as cleaning coils,
or cleaning and replacing filters. All other operations should be performed by trained
personnel only. When working on heating equipment, observe precautions in the
literature, on tags, and on labels attached to the unit.
Follow all safety codes. Wear safety glasses and work gloves. Have a fire extinguisher
available.
CAUTION!
:
Before beginning the installation or modification, be sure the main
electrical disconnect switch is in the OFF position.
CAUTION!
:
Failure to carefully read and follow these instructions before servicing
or operating this control, could result in personal injury, death and/or
property damage.
Safety Considerations
Operational Differences and Added Features
The following is a description of the slight operational differences and added
features. Refer to
ICM275
Component Layout (Page 3) for location of control center
components.
Installation Instructions
CAUTION!
:
Verify power is removed from the control by removing fuse or turning
off circuit breaker.
1. Disconnect wiring from blower control center. Tag each wire as it is disconnected
from the old furnace control center. Disconnect
all
wiring hookups.
2. Remove existing blower control center.
3. Install the
ICM275
fan control center into the control center box. Be sure that the top
edge of the
ICM275
is in the mounting slot, just like the original board.
CAUTION!
:
If the
ICM275
is not installed correctly (i.e.: behind the slot), an
electrical short could occur.
4. Reconnect all of the wire(s) that were removed in Step 1 above, to the proper
terminals.
5. Turn power to ON position and check unit sequence of operation per unit installation
instructions.
6. These instructions must be placed with the original unit instruction packet, or with
the unit for future reference.
Blower Operating Modes
Input From
Thermostat
Resistor (R18) Uncut
Resistor (R18) Cut
W
Lo-speed heating blower*
Lo-speed heating blower*
G
Hi-speed cooling blower
Lo-speed heating blower
Y
No blower
Hi-speed cooling blower**
* 60-second ON delay
and 60-240 second
adjustable OFF delay
** 90-second OFF delay
EAC-2
EAC-1
R
W
ATO
3-amp
Fuse
H
Y
GH
C
G
EAC-2
EAC-1
SEC-1
SEC-2
INC
240
R18
COM
L2
PR2
LO
HI
PR1
L1
LED1
NO
NC
C
COIL
NO
C
COIL
NO
C
NC
FORM-C
SPCB-1
PCB503-1
TEST
ST
A
TUS
G-BLOWER
OPTION
Resistor (R18)
PT1
K2
F1
3A ATO
Blower Of
f Delay Pot
ATO 3-amp Fuse
JW1
Component Layout
Operation with new blower and humidifier relays:
The previous design control centers used a SPST-NC or DPST-NC heating fan relay
(HFR of E2) and a DPDT cooling fan relay (CFR or 2F) for blower and humidifier
terminal operation. This new control center uses a SPST-NO blower relay (BLWR)
and a SPDT blower speed change relay (hi/lo) for blower operation, and a SPST-NO
humidifier relay.
1. The low-speed blower will not operate on a transformer failure as on previous
designs.
2. If
JW1
jumper is cut between
R
and
GH
terminals, a constant low-speed blower
will occur without any thermostat inputs to the control center. A
GC
or
Y
signal to
the control center
will not
bring on the hi-speed blower for cooling operation.
JW1
jumper
must not
be cut on cooling applications.
3. The humidifier
H
terminal is energized with low-speed blower operation. In cooling
operation, the humidistat and humidifier water supply should be turned off to ensure
the humidifier does not operate.
24 volt circuit protection:
An automotive type, 3 amp fuse is provided to protect the transformer and thermostat
from shorts in the low-voltage circuitry. An open fuse will initiate a constant low-speed
blower. Refer to the
ICM275
Component Layout (Page 3) for location on control center.
Low-speed continuous “G” blower and 90-second hi-speed blower OFF delay
option:
Resistor
(
R18
) on the control center can be cut to achieve heating speed continuous
blower with a thermostat (
R-G
) call and a hi-speed blower with a 90 second OFF delay
with a thermostat (
R-Y
) call.
CAUTION!
:
Do not cut R18
on
twinned
furnace applications.
